1. Technical Field
The disclosure relates to gas turbine engines.
2. Description of the Related Art
Gas turbine engines use compressors to compress gas for combustion. In particular, a compressor typically uses stages, each of which incorporates a row of rotating blades and a row of stationary vanes to compress gas. Gas flowing through such a compressor is forced between the rows and between adjacent blades and vanes of a given row. Similarly, after combustion, hot expanding gas drives a turbine that uses stages, each of which incorporates a row of stationary vanes and a row of rotating blades.
The flow rate through the turbine is set by adjusting the throat areas of the vanes and/or blades. Modifying the throat areas has the effect of changing the relationship between flow rate and pressure ratio of the engine. Changing the pressure ratio tends to have an effect on the operating temperatures of the engine and, therefore, affects engine performance. Therefore, manipulation of the throat areas may be desirable to adjust the aerodynamic characteristics of the gas turbine engine under certain operating conditions.